Hi i'm new here and this is my first replie. (sry for my poor english)
I try to improve jump and sprint performance since three years now.
I think hip movement is the most important factor in sprinting and single leg jumping.
For example stand on a weight scale and drive your knee up as fast as you can. Look at the scale and you know what i mean.
For me it's unbelieveable that no one trains the hipflexors. There are millions of youtube vid with heavy lifts like squats and deadlifts and all that stuff, but no hipflexor exercises like one leg weighted situps or weighted leg raises. poor!
The two most important musclegroups are the hip flexors and the two jointed hamstrings.
The quads aren't very important in RSL movements. Most of you won't beliebe this.
the quads are hip flexors..
Doing MaxEffort bulgarin split squats with dbs makes your two-joined hamstrings extreme sore! But not your quads!
Because the power come from the hips. It's very important to have a super strong core to transfer the power!
the quads rarely get sore with any lift, they are pretty much always stronger than the hamstrings.
I think the reason is because the hip joint is a fix point. One leg drives forward (hipflexor work) and the other backwards (hamstring and little glute work) this result in a fix hip joint position.
The sprint trainer barry ross write an article: http://www.dragondoor.com/articler/mode3/269/
And i read a study about the corelation of hamstring strenght and sprint times. That's also a reason why deadlifts are great for sprinting especially SL deadlifts.
sure hamstrings are more important for sprinting than jumping, the quads still absorb a ton of force during each foot contact during a sprint, and stabilize the patella.
End result: hip movement have highest priority in sprinting/ SLRJ for me
calv movement have second highest.
sprinting/SLRVJ have more contribution from hamstrings, for sure.. for double leg jumping, quads become extremely important.. regardless, quads always absorb a majority of the force in each movement.
as for hip flexors, sure training them directly may help in SLRVJ, most definitely will help with sprinting, but for double leg jumping, not so important.. hip flexors get strong and powerful simply by sprinting, for the most part.
peace